In postmenopausal women, obesity, falls, unknown osteoporosis status, and osteoporosis are associated with high risk of distal radius fracture. If comorbidities and advanced age are also present, this group of persons may be at higher risk for unstable distal radius fractures.

Background Senile osteoporosis with age-related bone loss is diagnosed depending on radiographic changes of bone and bone mineral density (BMD) measurement. However, radiographic alterations are usually signs of medium-late stage osteoporosis. Therefore, biomarkers have been proposed as indicators of bone loss. In the current study, Galectin-1 (Gal-1) showed age-related decline in mice serum. The role of Gal-1 in osteoporosis has not been investigated so far. Hence, the current study illustrated the relationship of serum Gal-1 level with bone loss. Methods We employed 6- and 18-month-old mice to establish an animal model of age-related trabecular bone loss, whose bone density and microstructure were investigated by micro-CT. ELISA was used to measure the levels of Gal-1 in serum. The correlation analysis was performed to illustrate the relationship between serum Gal-1 levels and trabecular bone loss. In addition, immunohistochemistry was used to investigate the abundance of Gal-1 in bone marrow of mice. ELISA and western blot were performed to measure the secretion ability and protein expression of Gal-1 in bone marrow stromal cells (BMSC), hematopoietic stem cells (HSC) and myeloid progenitor (MP) respectively. Flow cytometry was used to measure BMSC number in bone marrow. Finally, male volunteers with age-related BMD decrease were recruited and the relationship between serum Gal-1 and BMD was analyzed. Results Gal-1 showed age-related decline in mice serum. Serum Gal-1 was positively associated with BV/TV of femur, tibia and L1 vertebrae in mice. BMSC secreted more Gal-1 compared with HSC and MP. BMSC number in bone marrow was significantly lower in aged mice compared with young mice. Significant attenuation of Gal-1 protein expression was observed in BMSC and HSC from aged mice compared with young mice. Further, we found a decline in serum Gal-1 levels in men with age-related BMD decrease. There was positive correlation between BMD and serum Gal-1 levels in these men. Conclusions Age-related trabecular bone loss is associated with a decline in serum Gal-1 level in mice and men. Our study suggested Gal-1 had great potential to be a biomarker for discovering BMSC senescence, diagnosing early osteoporosis and monitoring trabecular bone loss.

To study the fracture network propagation mechanism in shale gas reservoirs and determine the influence of induced stress from the growth of multiple fractures, this paper describes the crack initiation pattern in a shale reservoir based on a core laboratory experiment and volume fracturing concept. In accordance with linear elastic fracture mechanics and based on the mathematical model of induced stress field with single fracture as reference, the rock surrounding stress equation of multiple fractures in a horizontal well was deduced. Prediction models of fracture pressure under different initiation patterns were established. Induced stress correction factor was proposed to simplify and correct the prediction models. Results demonstrate that the mechanical parameters of rock directly affect the fracture initiation pattern in shale reservoirs. Tensile failure on the bedding surface primarily occurs, along with shear slippage damage for brittle rocks, whereas shear was mainly observed in plastic rocks. The morphology and distribution of fractures are closely related to induced stress field. Simulation results show that induced stress is positively correlated with fracture height and negatively correlated with fracture interval. Dimensionless fracture interval between one to two is the "gold window" to create a fracture network in fracturing design. Minimum induced stress occurs at 30° and 150° with the minimum horizontal stress direction. The study significantly contributes in the research of crack initiation law and optimization of fracture design.